The purpose of this project is to examine non-head-to-tail monoterpene biosynthesis in plants as a model for more clearly defining the mechanism of head-to-head condensations (squalene synthesis). This approach will greatly simplify the synthesis of potential intermediates and facilitate the further enzymological study of this process. Although Artemesia ludoviciana appears to be a suitable source of material for cell-free, terpene enzyme isolations, screening of plants of the Compositae family will continue to search for better sources. A number of substrate analogs will be synthesized for study in the cell-free system in order to define the mechanism and active sites on the enzyme. On the basis of successful model studies analogous triterpene analogs will be synthesized and investigated in presqualene purophosphate biosynthesis.